Conventionally, a humidity control apparatus has been known, which is configured to control room humidity using an adsorbent. Patent Document 1 discloses, as the humidity control apparatus of this type, an apparatus configured to control room humidity using two adsorption heat exchangers on each of which an adsorbent is supported.
The humidity control apparatus includes a refrigerant circuit configured such that a compressor, an expansion mechanism, and the adsorption heat exchangers are connected together and that a refrigerant circulation direction is reversible, and an air passage configured such that an air flow path switches, depending on the refrigerant circulation direction in the refrigerant circuit, so as to cause one of room air or outdoor air to pass through one (i.e., a moisture-desorption adsorption heat exchanger) of the adsorption heat exchangers serving as a condenser and to cause the other one of room air or outdoor air to pass through the other one (i.e., a moisture-absorption adsorption heat exchanger) of the adsorption heat exchangers serving as an evaporator. In the humidity control apparatus, a humidification operation is performed, in which outdoor air is supplied to the inside of a room through the moisture-desorption adsorption heat exchanger and room air is discharged to the outside through the moisture-absorption adsorption heat exchanger.
In theory, in a refrigeration cycle, heat absorbed by refrigerant in an evaporator and a compressor is dissipated from the refrigerant in a condenser. However, since the moisture-absorption adsorption heat exchanger serving as the evaporator in the humidity control apparatus is mainly intended for dehumidification of room air, there is a possibility that a sufficient amount of heat absorbed by refrigerant cannot be ensured. On the other hand, in order to, e.g., recover the adsorbent, a certain amount of heat should be ensured in the moisture-desorption adsorption heat exchanger serving as the condenser. For such reasons, it is necessary to compensate for the lack of the amount of heat absorbed by refrigerant in the moisture-absorption adsorption heat exchanger with heat provided to refrigerant in the compressor. This may increase power consumption in the compressor, resulting in lowering of compressor efficiency.
In the humidity control apparatus of Patent Document 1, an air heat exchanger is connected between each adsorption heat exchanger and the expansion mechanism in the refrigerant circuit. In the humidification operation, one of the air heat exchangers serves as a subcooler configured to subcool refrigerant using outdoor air, and the other air heat exchanger serves as a heat-recovery heat exchanger configured to recover heat from room air. Thus, in the humidification operation, refrigerant can be subcooled in the subcooler, as well as recovering heat from exhaust air not only in the moisture-absorption adsorption heat exchanger but also in the heat-recovery heat exchanger. Accordingly, in the humidification operation, the required amount of heat dissipated to outdoor air can be fully ensured, and it is not necessary to compensate for the lack of the amount of heat absorbed by refrigerant in the moisture-absorption adsorption heat exchanger with heat provided to refrigerant in the compressor. As a result, lowering of compressor efficiency can be reduced.
In the humidity control apparatus, the subcooler in the flow of outdoor air and the heat-recovery heat exchanger in the flow of room air are both arranged downstream or upstream of the adsorption heat exchangers.